Inflator

ABSTRACT

An inflator of the augmented type includes a pressure vessel and a combustion chamber containing a gas generating charge of propellant and having a wall provided with an outlet opening to the pressure vessel. A cap telescopes over the combustion chamber and seats against a flat of the wall adjacent to the outlet. The cap is secured to the combustion chamber and mounts a rod for impacting a severable plug of the pressure vessel to open the plug and communicate the pressure vessel with an occupant restraint cushion when the charge of propellant is initiated and the resultant high pressure gases blow the cap from the opening.

United States Patent [191 Merrell Dec. 24, 1974 4] INFLATOR [75] Inventor: Richard L. Merrell, Huron, Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: June 25, 1973 [21] Appl. No.: 373,283

[52] US. Cl 222/5, 280/150 AB [51] Int. Cl. F170 7/00 [58] Field of Search 222/3, 5; 280/150 AB;

[56] References Cited UNITED STATES PATENTS 2,997,051 8/1961 Williams 222/5 X 3,663,036 5/1972 Johnson 222/5 X Primary ExaminerRobert B. Reeves Assistant Examiner-Francis J. Bartuska Attorney, Agent, or FirmHerbert Furman [57] ABSTRACT An inflator of the augmented type includes a pressure vessel and a combustion chamber containing a gas generating charge of propellant and having a wall provided with an outlet opening to the pressure vessel. A cap telescopes over the combustion chamber and seats against a flat of the wall adjacent to the outlet. The cap is secured to the combustion chamber and mounts a rod for impacting a severable plug of the pressure vessel to open the plug and communicate the pressure vessel with an occupant restraint cushion when the charge of propellant is initiated and the resultant high pressure gases blow the cap from the opening.

1 Claim, 1 Drawing Figure INFLATOR This invention relates generally to inflators of the augmented type and more particularly to such inflators having a combustion chamber separate from the pressure vessel and communicating with the pressure vessel across an outlet closed by a rupturable seal.

lnflators of the augmented type are well known. The rupturable seal controlling communication between the combustion chamber and the pressure vessel may either be integrally formed with the outlet wall of the combustion chamber or formed separately and secured to the wall.

Regardless of which type of seal is conventionally employed, the seal must be able to withstand the nominal working pressure of the gas or fluid within the pressure vessel, such as 2,400 psi and, of course, must be able to withstand the test pressure of the vessel when the vessel is filled, which is at least twice the nominal working pressure. This normally requires a high strength seal.

This invention provides a sealing arrangement for the outlet wall of the combustion chamber which permits a lower strength seal to be used since the seal is supported by the outlet wall of the combustion chamber. In the preferred embodiment of the invention, the outlet end of the combustion chamber is of reduced diameter and the outer surface of the outlet wall is of generally frustoconical shape, including a flat which contains the outlet and a tapered portion surrounding the flat and extending to the reduced diameter outlet end of the combustion chamber. A cap seal telescopes over the reduced diameter outlet end of the combustion chamber and has the flange thereof welded or otherwise fixed to the combustion chamber. The base wall of the cap seal is flat and seats against the flat of the outer surface of the outlet wall so as to be backed up or supported thereby around the outlet of the combustion chamber. A rod is fixed to the base wall coaxial with the outlet and is located so as to impact a severable or rupturable seal in the outlet wall of the pressure vessel and communicate the pressure vessel with an occupant restraint cushion. The base wall of the cap seal ruptures or fractures when the charge of propellant within the combustion chamber is initiated to thereby open the combustion chamber to the pressure vessel and simultaneously open the pressure vessel to the cushion.

One of the features of this invention is that it provides an improved sealing arrangement for the combustion chamber of an augmented type inflator. Another feature of this invention is that the sealing arrangement includes a rupturable member which is backed up or supported by the outlet wall of the combustion chamber. A further feature of this invention is that the sealing arrangement includes a cap seal which is telescoped over the outlet end of the combustion chamber and is secured thereto, with the base wall of the cap seal being seated upon and supported by a flat of the outlet end wall of the combustion chamber. Yet a further further feature of this invention is that the cap coaxially mounts an impact member for impacting a severable or rupturable seal of the pressure vessel in order to communicate the pressure vessel with an occupant restraint cushion when the base wall of the cap seal is ruptured upon initiation of the charge of propellant within the combustion chamber.

These and other features of the invention will be readily apparent from the following specification and drawing wherein:

FIG. 1 is a sectional view of an inflator according to this invention.

Referring now to the drawing, an inflator l0 according to this invention includes a cylindrical pressure vessel 12 which includes an integral wall 14 closing one end thereof. A cylindrical combustion chamber 16 fits within the pressure vessel and includes a wall 18 closing the inner end thereof and provided with a cylindrical outlet 20 coaxial with the combustion chamber. Wall 18 is of lesser OD than the chamber 16 and is joined thereto by a lesser OD wall portion 22 of the combustion chamber. The other end of the combustion chamber includes an outwardly flaring or conical wall 24 which terminates in a radial flange 26. Flange 26 seats against the other open end of the pressure vessel and is welded thereto at 28 in a conventional manner in order to close the pressure vessel. The pressure vessel is filled with any suitable gas under pressure, such as argon at 2,400 psi.

The combustion chamber 18 includes a cartridge assembly 30 which is disclosed in detail and claimed in copending applications Ser. No. 331,663, Charles N. Hay, filed Feb. 12, 1973, and Ser. No. 373,282, Philip B. Zeigler, filed June 25, 1973, both assigned to the assignee of this invention. Generally, the cartridge assembly 30 includes a cylindrical plastic housing 32 which fits within the combustion chamber and contains a cylindrical charge 34 of propellant which generates high pressure, high temperature gases when the charge is initiated. Propellants such as this are known in the art and therefore no further description is necessary. The outer integral end wall 36 of the housing 32 is substantially thick and is provided with a pair of bores 38 and 40. Bore 38 contains an igniter or initiating element 42 and bore likewise contains a squib 44. Retained within the bore 40 to the right of squib 44 is a conventional ball 46.

The inner end of the housing 32 includes a partial radial flange 48 which seats and retains a closure plate 50 having a central fluted orifice 52. The outlet 22, the orifice 52 and the ball 46 are coaxial. A seal plate 54 is secured to the wall 36 and mounts an electrical plug 56. The plug 56 is connected to the igniter 42 and squib 44 by electrical wires extending through the seal plate. The cartridge assembly is retained within the combustion chamber by a circular split ring 58 engaged in a semicircular groove in the combustion chamber wall and also engaged by the chamfered outer edge of the seal plate.

The plug 56 connects the igniter and squib with a known multi-level actuation system for a vehicle occupant restraint system. Such actuation systems can include a velocity responsive sensor and an inertia responsive sensor. Should the velocity responsive sensor or the inertial sensor sense low level impact conditions, the igniter 42 will be connected with the vehicle battery or other source of power to thereby initiate the charge 34 of propellant to generate high temperature, high pressure gases. Should the impact conditions sensed be of a higher level, then the squib 44 is connected to the same source of power to fire the ball 46 into the orifice 52. This restricts the orifice area and increases the pressure within the combustion chamber to increase the burn rate. The foregoing description is brief but reference may be had to the aforenoted copending applications for further details.

A cap seal 60 includes a base wall 62 and an axially extending flange or skirt 64. The skirt 64 telescopes over the wall portion 22 and abuts against a shoulder 66 formed between the wall portion 22 and the combustion chamber. The skirt 64 is welded at 68 to the combustion chamber. The base wall 62 of the cap seal 60 abuts against a circular flat wall portion 70 of wall 18 which surrounds the outlet 20. The flat portion 70 merges into a tapered circular wall portion 72 of the wall 18 so that the base wall 62 of the cap is supported only at its center portion and around the outlet 20. The wall portions 70 and 72 thus define a generally frustoconical surface.

An impact member or rod 74 is welded at one end to the wall 62 coaxial thereof. The other end of the rod is frictionally received within a split sleeve 76 which is received within a counterbore 78 of a s'everable or rupturable seal 80 in the outlet end wall 14 of the pressure vessel. The seal 80 is defined by opposed V cross section grooves 82 and 84 of wall 14.

From the foregoing description, it can be seen that the wall 62 of the cap 60 is backed up or supported by the wall portion 70 of wall 18. Thus, when the pressure vessel 12 is filled and tested, the wall portion 62 need not be able to solely or independently withstand the test pressure, since it is additionally supporoted or backed up. As previously mentioned, the nominal working pressure of the fluid within the vessel 12 can be 2,400 psi, but the test pressure is at least twice this pressure. By backing up the wall portion 62, a lower strength cap seal 60 can be used.

When the charge 34 of propellant is initiated by the squib 42, the generated gases increase the pressure within the combustin chamber 16. When this pressure exceeds a predetermined level, the wall portion 62 of the cap seal fractures or ruptures, normally at the juncture between this wall portion and the skirt 64, so that the outlet is now open to the pressure vessel 12. Simultaneously with this rupture of the wall portion 62, the rod 74 is shifted to the right to impact seal 80 and remove this sea] to open the pressure vessel 12 to the occupant restraint cushion. The pressure vessel opens to a tapered outlet member 86 which is welded at 88 to the wall 14 of the pressure vessel. A manifold 90 telescopes over the outlet member and is secured thereto by a nut 92 threaded on an integral threaded extension 94 of the outlet member. A plurality of radial openings 96 communicate the outlet member with the manifold. The manifold in turn communicates with a conventional diffuser 98 which distributes the pressure fluid to the occupant restraint cushion.

Thus, this invention provides an improved inflator.

I claim:

1. An inflator comprising, in combination, a generally cylindrical pressure vessel containing pressure fluid and having an outlet for communicating the inflator with an occupant restraint cushion, rupturable means closing the outlet, generally cylindrical combustion chamber coaxially within the pressure vessel and containing a charge of propellant for generating gas, the chamber including a generally radially extending end wall at one end thereof having an outer surface provided with a central flat portion and a surrounding tapered portion, the end wall including a normally open outlet through the flat portion communicating the combustion chamber with the pressure vessel, a diaphragm cap of thin frangible material telescoped over the end of the combustion chamber and including an axial wall surrounding and secured to the chamber and a radial wall seating on the flat portion of the outer surface of the end wall of the chamber around the outlet to close the outlet, the seating of the radial wall of the cap on the flat portion of the outer surface of the end wall supporting the radial wall against rupture by the pressure fluid within the pressure vessel, and rigid means mounted on the radial wall of the cap and projecting to adjacent the rupturable means for impacting and rupturing the rupturable means upon generation of gas within the combustion chamber and rupture of the radial wall of the cap. 

1. An inflator comprising, in combination, a generally cylindrical pressure vessel containing pressure fluid and having an outlet for communicating the inflator with an occupant restraint cushion, rupturable means closing the outlet, generally cylindrical combustion chamber coaxially within the pressure vessel and containing a charge of propellant for generating gas, the chamber including a generally radially extending end wall at one end thereof having an outer surface provided with a central flat portion and a surrounding tapered portion, the end wall including a normally open outlet through the flat portion communicating the combustion chamber with the pressure vessel, a diaphragm cap of thin frangible material telescoped over the end of the combustion chamber and including an axial wall surrounding and secured to the chamber and a radial wall seating on the flat portion of the outer surface of the end wall of the chamber around the outlet to close the outlet, the seating of the radial wall of the cap on the flat portion of the outer surface of the end wall supporting the radial wall against rupture by the pressure fluid within the pressure vessel, and rigid means mounted on the radial wall of the Cap and projecting to adjacent the rupturable means for impacting and rupturing the rupturable means upon generation of gas within the combustion chamber and rupture of the radial wall of the cap. 